You will find dolphin(dauphin) springing outside the water. This beautiful constellation is visible between in the middle of May and in the middle of November, more or less low on the horizon. One, two, three, four, five, six and seven: here is dolphin(dauphin) in the bare eye. Two stars draw the tail, four others the body, and a last one the snout. It is the one who interests us because it is about a double star. You are there? It names Gamma Delphini (there Delphini). Both stars, distant from an angle of 10,44 " of bow (longitude), are relatively close; with magnitude of 4,5 and 5,5, they are normally visible in the bare eye both, but that is not the case. The one is blue, the other one is yellow. A beautiful program of observations in perspective.

Longitude: angular distance in a meridian of origin, eastward or the West.

Magnitude:Grandeur is similar (of a celestial body), characterized by a number.